HDR to SDR Display Mapping via Luminance Metadata
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Solution Overview
Problem
Existing image processing methods for high-dynamic-range (HDR) images lose significant information during dynamic range conversion from HDR to standard dynamic range (SDR) when using simple linear scaling, resulting in a different visual effect for the viewer, which is not intended by content producers.
Innovation Solution
An image processing apparatus and method that generate and utilize metadata-based luminance conversion information to adapt HDR content to the capabilities of the display output destination, including the use of one-dimensional look-up tables (1D-LUTs) and supplemental enhancement information (SEI) to preserve the intent of the content producer, ensuring accurate dynamic range conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simple linear scaling is used for dynamic range conversion, then the conversion process is simple and fast, but a great amount of information is lost and the visual effect becomes greatly different from the original
Solution Approach 1:
The content producer performs luminance conversion in advance during content creation, generating SDR content from HDR content while preserving the intended visual effect. This preliminary conversion allows the original HDR content and its visual intent to be captured and stored as metadata, which can then guide subsequent display mapping without requiring complex real-time conversions that lose information.
Solution Approach 2:
Metadata acts as an intermediary that carries the content producer's luminance conversion intent from the content creation stage to the display stage. Instead of directly converting HDR to SDR at display time (which loses information), the metadata serves as a mediator that preserves the original visual intent and guides the display mapping process to reproduce it accurately.
2Device complexity
If simple linear scaling is used for dynamic range conversion, then the processing complexity is low, but the visual effect greatly differs from what the content producer intended
Solution Approach 1:
The content producer performs luminance conversion in advance during content creation, generating SDR content from HDR content while preserving the intended visual effect. This preliminary conversion allows the original HDR content and its visual intent to be captured and stored as metadata, which can then guide subsequent display mapping without requiring complex real-time conversions that lose information.
Solution Approach 2:
The system uses feedback from the originally converted SDR content to guide the display mapping process. By comparing the original HDR content with its SDR conversion, the system learns the content producer's luminance mapping intent and applies this feedback during display mapping to accurately reproduce the intended visual effect while adapting to different display capabilities.
3Adaptability or versatility
If HDR content is converted to SDR without preserving conversion intent, then the content can be displayed on any display, but the visual effect is significantly degraded
Solution Approach 1:
The system provides universal display compatibility by supporting both HDR and SDR displays through a unified approach. The content is originally created in HDR format and can be displayed on HDR-capable displays with full dynamic range, or on SDR displays with accurate visual effect preservation through metadata-guided display mapping. This multi-functional approach eliminates the need for separate HDR and SDR content versions.
Solution Approach 2:
Metadata acts as an intermediary that carries the content producer's luminance conversion intent from the content creation stage to the display stage. Instead of directly converting HDR to SDR at display time (which loses information), the metadata serves as a mediator that preserves the original visual intent and guides the display mapping process to reproduce it accurately.
Data Source
AI summary
An image processing apparatus and an image processing method which can transmit/receive or display a high-dynamic-range image suitably are provided. An image transmission apparatus transfers, as metadata of content, luminance conversion information, which is for conversion of HDR content (for example, with maximum luminance 2000 nit) into SDR content (having, for example, 100 nit), or differential information. Based on the metadata, an image reception apparatus generates luminance conversion information, in which received HDR content is adapted to a capability of a display (for example, with maximum luminance 500 nit or 1000 nit) in an output destination, and realizes display mapping which is not against an intention of a producer.